How do I uninstall an Addon added by running a Python Script?
I don't think you can uninstall it as you didn't technically install it if you said you 'ran the script'. Best you can do is close and re-open file I think.

Edit:

I found that the script had also been added to my startup file without me having saved it. On windows I navigated to:

C:\Users\USERNAME\AppData\Roaming\Blender Foundation\Blender\2.70\scripts\addons\__pycache__\


I deleted a file with object_creaprim in the file name and reloaded blender and it disappeared.